如何将所有类别的总和插入到mysql中？

Question

我有这样的数据

  category        expense       monthyear
--------------------------------------------------------------------------
 1. food           1000           Dec2015
2.  movie          100            Dec2015
3.  housing        2000           Dec2015
4  .food           1000           Dec2015
5  .housing        2000           Dec2015
6.  food           1000           Dec2015

当我插入数据库时​​，我希望得到每个类别费用的总和，如：food-3000,movie-100,housing-4000

如何编写查询，即时在codeigniter框架中进行？

Answer 1

您需要的基本查询结构是：

INSERT INTO expensetotals (category_total, exp_total)
SELECT category AS category_total, SUM(expense) AS exp_total
FROM expenses
GROUP BY category

新表格“expensesetotals”如下所示：

category_total       exp_total
------------------------------
food                 3000
housing              4000
movie                100

Answer 2

我不熟悉CodeIgnitor，但根据您的问题，您可以尝试此查询

  INSERT INTO categorysum(category, amount) SELECT category, sum(expense) FROM current_table WHERE 1 GROUP BY category